Rotation mechanism



mmm

W. A. 8MKTH, SR

ROTATION MECHANISM Filed March 14, 1936 H i 5 ATTORNEY.

Mwr'ch 1,, mm

Patented Mar. 1, 1938 STATES ATENT ()FFI'QE ROTATION MECHANISM Application March 14, 1936, Serial No. 68,830

'7 Claims.

This invention relates to rock drills, and more particularly to rotation mechanism for rock drills of the reciprocatory hammer type.

One object of the invention is to impart a stepby-step rotary movement to the working implement in order to change its position prior to the delivery of each blow of the percussive element thereagainsh Another object is to assure prompt engagement and disengagement between the locking elements of the rotation mechanism at the most suitable period in the cycle of operations of the hammer piston.

Other objects will be in part obvious and in part pointed out hereinafter.

In the drawing accompanying this specification and in which similar reference numerals refer to similar parts,

Figure l is an elevation in section of a rock 2o drill embodying rotation mechanism constructed in accordance with the practice of the invention, and

Figures 2 and 3 are transverse views taken through Figure l on the line 2-2 showing the 25 rotation mechanism in the released and engaging positions, respectively.

Referring more particularly to the drawing, the invention is shown embodied in a rock drill comprising as casing parts, a cylinder 20, a front head 2! and a back head 22.

The cylinder is bored to provide a piston chamber 23 for the accommodation of a reciprocatory hammer piston 24. The piston has a stem 25 which extends through a closure 26 in the front end ofthe cylinder and into the front head 2! to deliver blows against a working implement 2? guided by and interlocked with a chuck 28 rotatable in the front head. The chuck 28 and the stem 25 are provided with ribs 29 and 3B which interlockingly engage each other to prevent relative rotation between the piston and the chuck.

In the rear end of the cylinder 2i] is an enlarged recess 3! which is sealed at its rearward end by the back head 22 and serves as a receptacle for valve mechanism 32 and rotation mechanism 33.

The valve mechanism which is disposed adjacent the rear end of the piston chamber 23, and forms a closure therefor, comprises a valve chest 34 which is recessed to provide a valve chamber 35 containing an oscillatory plate type valve 35. The valve 36 controls the admission of pressure fluid into the inlet passages 31 and 38 leading from the valve chamber 35 to the rear and front ends, respectively, of the piston chamber. The pressure fluid employed for this purpose is conveyed to the valve chamber by a supply passage 39 leading from a reservoir 40 in the back head to the valve chamber 35, and flows to the supply reservoir by a passage 4| leading from a throttle valve 42 in the back head 22.

The pressure fluid used for actuating the piston 24 is exhausted from the piston chamber 23 through an exhaust port 44 controlled by the piston 20. t

The rotation mechanism 33 employed for imparting a step-by-step rotative movement of the hammer piston and constructed in accordance with the practice of the invention comprises a ring 45 seated upon the valve mechanism 34 and secured to the cylinder, as by a pin 46 embedded partly in the ring and partly in the cylinder.

Within the ring 45 is the head 4'! of a rifle bar 48 which extends through the valve mechanism 20 and is slidably interlocked with the piston 24 in a 'well known manner. The head 41 is of smaller diameter than the interior of the ring 45 to define an annular chamber 49 therebetween for the reception of friction or braking elements 50. The friction elements are in the form of ring segments which are preferably of slightly less thickness than the width of the chamber 49 so that they will be capable of a slight degree of lateral movement in the chamber; 30

The outer surfaces 5b of the segments 50 are roughened, as by knurling, in order to break up any oil film which may exist on the inner surface of the ring, thereby assuring firm and prompt engagement of the segments with the ring 45.

In the form of the invention illustrated only two segments are shown and, in order to maintain them in constant readiness for frictional engagement with the ring 45; spring-pressed plungers 52 are disposed radially in the head 4! to exert slight pressure against the intermediate portions of the segments 50 and thereby press the surfaces 5| lightly against the ring 45.

The adjacent ends of the segments 50 are parallel and spaced with respect to each other to define therebetween spaces 53 into which extend the outer ends of spreaders 54. The spreaders are preferably in the form of rectangular plates presenting opposed fiat surfaces 55 and 56 which seat against the ends of the segments 50. The opposite ends of the spreaders extend loosely into notches 51 in the head 41.

The entrance and rear or inner ends of the notches 51 are flared in opposite directions to provide an intermediate narrow portion 58 in each notch of approximately the width of the spreaders to act as fulcrums therefor. The extremities of the spreaders are suitably curved to enable the spreaders to oscillate freely Without hindrance from the adjacent surfaces.

The operation of the device is as follows: Let it be assumed that the piston 24 is in its foremost limiting position and about to initiate its rearward stroke. Being slidably interlocked with the rifle bar 38, the piston, at the instant of starting, imparts a slight rotary movement to the rifle bar and causes the head i? to tilt the spreaders The outer ends of the spreaders will then act against the ends of the segments 50 and force the knurled surfaces 5! into firm frictional engagement with the ring Q5. In this way the rifle bar f8 will be locked against rotation and, during its rearward stroke, the piston will describe a partial revolution and shift the working implement to a new position preparatory to the delivery of a blow of the piston thereagainst.

At the instant of reversal of the piston in. the rear end of the piston chamber the rifle bar is rotated sufficiently in an oppostie direction to relieve the pressure of the Spreaders against the ends of the segments 58, thereby breaking the frictional engagement between the segments and the ring 55. The rifle bar may then rotate freely as the piston proceeds on its working stroke and will not, therefore, hinder the speed of the piston, and during the reverse movement of the rifle bar the segments 50 will be rotated to a new position with respect to the ring i5 by the spreaders 54.

In practice, the present invention has been found to function in an exceedingly eflicient manner. The gripping element of the rotation mechanism is quickly responsive to changes in the direction of travel of the piston which controls the rotation mechanism. A wide area of frictional contact exists between the segments and the ring member so that wear caused by long service of these elements will be negligible.

I claim:

1. In a rock drill having a casing and a piston therein, rotation mechanism for the piston comprising a stationary ring, a rifle bar interlockingly engaging the piston, a head on the rifle bar lying Within the ring, friction members arranged loosely about the periphery of the head, means tiltably interlocked with the head and arctuated thereby to force the friction members into frictional engagement with the stationary ring for locking the rifle bar thereto during one stroke of the piston and to release the friction members to relieve friction between said members and the ring for releasing the rifle bar during the succeeding stroke of the piston, thereby causing the piston to described intermittent partial revolutions, and fulcra in the head engaging the said means to cause tilting movement of said means.

2. In a rock drill having a casing and a piston therein, rotation mechanism for the piston comprising a stationary member in the casing having a bearing surface, a rifle bar interlockingly engaging the piston and extending into the stationary member, friction members interposed between the rifle bar and the stationary member, means carried by the rifle bar for forcing the friction members into frictional engagement with the bearing surface, thereby preventing rotation of the rifle bar and causing the piston to describe a partial revolution, and means acting against the intermediate portions of the friction members for constantly pressing the friction members against the stationary member.

3. In a rock drill having a casing and a piston therein, rotation mechanism for the piston comprising a stationary member in the casing having a bearing surface, a rifle bar interlockingly engaging the piston and extending into the stationary member, friction means interposed between the rifle bar and the stationary member, and means tiltingly interlocked with the rifle bar and the friction means and being actuated by the rifle bar for moving the friction means along the bearing surface upon movement of the piston in one direction and for pressing the friction means into frictional engagement with the bearing surface upon movement of the piston in the opposite direction, thereby preventing rotation of the rifle bar and causing the piston to describe a partial revolution.

4. In a rock drill having a casing and a piston therein, rotation mechanism for the piston comprising a stationary member in the casing having a bore, a rifle bar interlockingly engaging the piston, a head on the rifle bar lying in the bore and cooperating with the stationary member to define an annular chamber therebetween, ring segments in the annular chamber, and means tiltable in the head acting against the ends of adjacent segments for moving the ring segments along the surface of the bore during movement of the piston in one direction and to force said segments into frictional engagement with the stationary member to prevent rotation of the rifle bar during movement of the piston in the opposite direction and thereby cause the piston to describe a partial revolution.

5. In a rock drill having a casing and a piston therein, rotation mechanism for the piston comprising a. stationary member in the casing having a bore, a rifle bar interlockingly engaging the piston, a head on the rifle bar lying in the bore and cooperating with the stationary member to define an annular chamber therebetween, ring segments in the annular chamber, and means seated tiltably in the head for moving the ring segments along the surface of the bore upon rotation of the rifle bar in one direction and extending between the ends of adjacent segments whereby upon slight rotational movement of the rifle bar in the opposite direction the segments are forced into flrm frictional engagement with the stationary member to lock the rifle bar to the stationary member.

6. In a rock drill having a casing and a piston therein, rotation mechanism for the piston comprising a stationary member in the casing having a bore, a rifle bar interlockingly engag ing the piston, a head on the rifle bar lying within the bore, friction members disposed between the head and the stationary member, means tiltingly interlocked with and actuated by the rifle bar to force the friction members into frictional engagement with the stationary member to lock the rifle bar to the stationary member, and fulcra in the head engaging the intermediate portions of said means to cause tilting movement of said means.

7. In a rock drill having a casing and a piston therein, rotation mechanism for the piston comprising a stationary ring, a rifle bar interlockingly engaging the piston, a head on the rifle bar lying within the ring, ring segments between the head and the stationary ring and having knurled surfaces adapted to seat against the ring, means tiltingly interlocked with the head and the segments to actuate the segments for pressing the knurled surfaces into frictional engagement with the stationary ring, thereby preventing rotation of the rifle bar and causing the piston to describe a partial revolution, and spring-pressed plungers in the head constantly acting against the intermediate portions of the ring segments to press said ring segments against the stationary ring.

WILLIAM A. SMITH, SR. 

